3.5. Pre-Partitioning for Multi-Boot Systems

Partitioning your disk simply refers to the act of breaking up your
disk into sections. Each section is then independent of the others.
It's roughly equivalent to putting up walls inside a house; if you add
furniture to one room it doesn't affect any other room.

If you already have an operating system on your system
(Windows 9x, Windows NT/2000/XP/2003/Vista/7, OS/2, MacOS, Solaris, FreeBSD, …)
and want to stick Debian on the same disk, you will need to repartition
the disk. Debian requires its own hard disk partitions. It cannot be
installed on Windows or MacOS partitions. It may be able to share some
partitions with other Unix systems, but that's not covered here. At
the very least you will need a dedicated partition for the Debian
root.

You can find information about your current partition setup by using
a partitioning tool for your current operating system, such as fdisk or PartitionMagic. Partitioning tools always
provide a way to show existing partitions without making changes.

In general, changing a partition with a file system already on
it will destroy any information there. Thus you should always make
backups before doing any repartitioning. Using the analogy of the
house, you would probably want to move all the furniture out of the
way before moving a wall or you risk destroying it.

If your computer has more than one hard disk, you may want to dedicate
one of the hard disks completely to Debian. If so, you don't need to
partition that disk before booting the installation system; the
installer's included partitioning program can handle the job nicely.

If your machine has only one hard disk, and you would like to
completely replace the current operating system with Debian GNU/Linux,
you also can wait to partition as part of the installation process
(Section 6.3.3, “Partitioning and Mount Point Selection”), after you have booted the
installation system. However this only works if you plan to boot the
installer system from tapes, CD-ROM or files on a connected machine.
Consider: if you boot from files placed on the hard disk, and then
partition that same hard disk within the installation system, thus
erasing the boot files, you'd better hope the installation is
successful the first time around. At the least in this case, you
should have some alternate means of reviving your machine like the
original system's installation tapes or CDs.

If your machine already has multiple partitions, and enough space can
be provided by deleting and replacing one or more of them, then you
too can wait and use the Debian installer's partitioning program. You
should still read through the material below, because there may be
special circumstances like the order of the existing partitions within
the partition map, that force you to partition before installing
anyway.

If your machine has a FAT or NTFS filesystem, as used by DOS and Windows,
you can wait and use Debian installer's partitioning program to
resize the filesystem.

If none of the above apply, you'll need to partition your hard disk before
starting the installation to create partitionable space for
Debian. If some of the partitions will be owned by other operating
systems, you should create those partitions using native operating
system partitioning programs. We recommend that you do
not attempt to create partitions for Debian GNU/Linux
using another operating system's tools. Instead, you should just
create the native operating system's partitions you will want to
retain.

If you are going to install more than one operating system on the same
machine, you should install all other system(s) before proceeding with
Debian installation. Windows and other OS installations may destroy
your ability to start Debian, or encourage you to reformat non-native
partitions.

You can recover from these actions or avoid them, but installing
the native system first saves you trouble.

If you currently have one hard disk with one partition (a common setup
for desktop computers), and you want to multi-boot the native
operating system and Debian, you will need to:

Back up everything on the computer.

Boot from the native operating system installer media such as CD-ROM
or tapes.

Use the native partitioning tools to create native system
partition(s). Leave either a place holder partition or free space for
Debian GNU/Linux.

Install the native operating system on its new partition.

Boot back into the native system to verify everything's OK,
and to download the Debian installer boot files.

Boot the Debian installer to continue installing Debian.

3.5.1. Partitioning From DOS or Windows

If you are manipulating existing FAT or NTFS partitions, it is
recommended that you either use the scheme below or native Windows or
DOS tools. Otherwise, it is not really necessary to partition from DOS
or Windows; the Debian partitioning tools will generally do a better
job.

But if you have a large IDE disk, and are not using LBA addressing,
overlay drivers (sometimes provided by hard disk manufacturers), or a
new (post 1998) BIOS that supports large disk access extensions, then
you must locate your Debian boot partition carefully. In this case,
you will have to put the boot partition into the first 1024 cylinders
of your hard disk (usually around 524 megabytes, without BIOS
translation). This may require that you move an existing FAT or NTFS
partition.

3.5.1.1. Lossless Repartitioning When Starting From DOS, Win-32 or OS/2

One of the most common installations is onto a system that already
contains DOS (including Windows 3.1), Win32 (such as Windows 95, 98, Me,
NT, 2000, XP, 2003, Vista, 7), or OS/2, and it is desired to put Debian onto the same disk
without destroying the previous system. Note that the installer supports
resizing of FAT and NTFS filesystems as used by DOS and Windows. Simply
start the installer and when you get to the partitioning step, select the
option for Manual
partitioning, select the partition to resize, and specify its new size.
So in most cases you should not need to use the method described below.

Before going any further, you should have decided how you will be
dividing up the disk. The method in this section will only split a
partition into two pieces. One will contain the original OS and the
other will be used for Debian. During the installation of Debian, you
will be given the opportunity to use the Debian portion of the disk as you
see fit, i.e., as swap or as a file system.

The idea is to move all the data on the partition to the beginning,
before changing the partition information, so that nothing will be
lost. It is important that you do as little as possible between the
data movement and repartitioning to minimize the chance of a file
being written near the end of the partition as this will decrease the
amount of space you can take from the partition.

The first thing needed is a copy of fips.
Unzip the archive and copy the files
RESTORRB.EXE, FIPS.EXE and
ERRORS.TXT to a bootable floppy. A bootable floppy can
be created using the command sys a: under DOS.
fips comes with very good documentation which you may
want to read. You will definitely need to read the documentation if
you use a disk compression driver or a disk manager. Create the disk
and read the documentation before you defragment the disk.

The next thing needed is to move all the data to the beginning of the
partition. defrag, which comes standard with DOS 6.0 and
later, can easily do the job. See the fips documentation
for a list of other software that may do the trick. Note that if you
have Windows 9x, you must run defrag from there, since
DOS doesn't understand VFAT, which is used to support for long
filenames, used in Windows 95 and higher.

After running the defragmenter (which can take a while on a large
disk), reboot with the fips disk you created in the
floppy drive. Simply type a:\fips and follow the directions.

Note that there are many other partition managers out there, in
case fips doesn't do the trick for you.

3.5.1.2. Partitioning for DOS

If you are partitioning for DOS drives, or changing the size of DOS
partitions, using Debian tools, many people experience problems working
with the resulting FAT partitions. For instance, some have reported
slow performance, consistent problems with scandisk, or
other weird errors in DOS or Windows.

Apparently, whenever you create or resize a partition for DOS use,
it's a good idea to fill the first few sectors with zeros. You should do
this prior to running DOS's format command by executing
the following command from Debian: